In automotive manufacture considerable attention is paid to driver safety requirements. One measure adopted in this regard resides in the use of bi-directional communication, for example by deploying high frequency signals (RF) to indicate to the driver any alarm or warning situation that may be emitted from the vehicle on a mobile RF transmitter/receiver device, e.g. vehicle key, the latter also being designated as a mobile identification (ID) provider.
Past solution strategies have stipulated that the vehicle must be actively transmitting and the key must always be on stand-by to receive, i.e. in so-called “polling” mode. As regards the key, the basic problem as far as this function is concerned is that of power/energy consumption. Even though the vehicle is actively transmitting and the key is only in receiving mode and average current consumption is reduced by approx. 1/10th to 1/50th of the active current for the receiver, there is still a not inconsiderable degree of energy consumption. Activation of the alarming function on the key is, with established battery technologies (small battery dimensions), only possible for a few days before it becomes necessary to change or to charge a battery.
In addition, certain problems emerge in the event of an alarm due to the actively transmitting vehicle which, during transmission, will be unable to receive any commands or information from associated vehicle keys or other ID providers.
The above problems are so far unresolved. Known alarming systems universally utilize polling technology. As a rule battery/rechargeable battery concepts are used which call for frequent recharging.